In a physical network, network functions and services are defined by network standard protocols and implemented by physical network devices. Network device vendors provide handy tools for diagnosing the network devices. When a network issue occurs, a user (e.g., a network administrator) can diagnose the network according to the standard protocols and runtime network topology using diagnosis tools provided by the device vendors. In a distributed virtual network (i.e., a logical network), however, network functions and services are implemented by logical forwarding elements (LFEs). Unlike the physical networks, the logical network topology cannot be used directly to diagnose network issues. This is because an LFE (e.g., a logical switch, a logical router, etc.) spans several different physical nodes and as such, the source of the network issue could be any one of the different physical nodes across which, the LFE spans (i.e., the physical nodes on which, the LFE is implemented).